Just wanted to let interested people know that we've recently released a Linux freeware version of SparcStation 20 emulator. It emulates SS20 with some basic peripherals: a single SPARC V8 32bit CPU, up to 512MB RAM, an NCR53C94 SCSI controller, 2 serial lines, disks, a network adapter, and a CDROM.
OS version supported: SunOS 4.1, Solaris 2.5 - 7 (2.3 and 2.4 are not supported at the moment).
Download is available form Stromasys website (registering your email would be required).
I tried it out as I have an interest in SPARC emulators for a number of reasons.
By the way, I can confirm that it works on Fedora 16. The Java terminal emulator is a bit flaky - maybe because it is Open JDK by default. Would be nice if a more-up-to-date and complete version of OBP was provided. You can get the full SMI sources for openboot 4.23.0 at coreboot.org. It was donated by SMI.